Electrosurgical wand and related method and system

ABSTRACT

Electrosurgical wand. At least some of the illustrative embodiment are electrosurgical wands including: an elongate housing that defines a handle end and a distal end; an aspiration aperture on the distal end of the elongate housing the aspiration aperture fluidly coupled to a first fluid conduit, the first fluid conduit within the elongate housing; a discharge aperture on the distal end of the elongate housing, the discharge aperture fluidly coupled to a second fluid conduit, and the second fluid conduit within the elongate housing; a first active electrode of conductive material on the distal end of the elongate housing, the first active electrode between the discharge aperture and the aspiration aperture; and a conductive plate that abuts the discharge aperture, at least a portion of the conductive plate disposed over the discharge aperture.

CROSS-REFERENCE TO RELATED APPLICATIONS

None.

BACKGROUND

In the treatment of chronic wounds (e.g., diabetic foot ulcers)electrosurgical procedures may be used to promote healing. Inparticular, electrosurgical procedures may be used for debriding thewound, inducing blood flow to the wound, coagulating blood flow from thewound, removing necrotic tissue, and/or removing bacterial films whichmay form (the bacterial films sometimes referred to as “biofilm”). Inmany cases wounds are considered “dry” in the sense that there isinsufficient conductive fluid present to support plasma creation forelectrosurgical procedures. In such cases a conductive fluid (e.g.,saline) is provided to help support plasma creation.

However, in providing a conductive fluid to a wound to help supportplasma creation, the location of the wound and/or the orientation of thepatient may adversely impact how the conductive fluid is distributed.For example, gravity may cause the conductive fluid to flow in such away as to not fully “wet” one or more of the electrodes involved in theplasma creation, thus limiting or preventing plasma creation.

Any advance that better controls distribution of conductive fluid in andaround the electrodes of an electrosurgical system would provide acompetitive advantage.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of exemplary embodiments, reference will nowbe made to the accompanying drawings in which:

FIG. 1 shows an electrosurgical system in accordance with at least someembodiments;

FIG. 2A shows a perspective view a portion of a wand in accordance withat least some embodiments;

FIG. 2B shows a cross-sectional view taken substantially along line2B-2B of FIG. 2A;

FIG. 3 shows a front elevation view of a wand in accordance with atleast some embodiments;

FIG. 4 shows a side elevation view of a wand in accordance with at leastsome embodiments;

FIG. 5 shows a side elevation view of a wand in accordance with at leastsome embodiments;

FIG. 6 shows a cross-sectional view taken substantially along line 6-6of FIG. 3;

FIG. 7 a side elevation view of a wand in operational relationship to awound in accordance with at least some embodiments;

FIG. 8 shows a front elevation view of a wand in accordance with atleast some embodiments;

FIG. 9 shows a front elevation view of a wand in accordance with atleast some embodiments;

FIG. 10 shows both an elevation end-view (left) and a cross-sectionalview (right) of a wand connector in accordance with at least someembodiments;

FIG. 11 shows both an elevation end-view (left) and a cross-sectionalview (right) of a controller connector in accordance with at least someembodiments;

FIG. 12 shows an electrical block diagram of an electrosurgicalcontroller in accordance with at least some embodiments; and

FIG. 13 shows a method in accordance with at least some embodiments.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claimsto refer to particular system components. As one skilled in the art willappreciate, companies that design and manufacture electrosurgicalsystems may refer to a component by different names. This document doesnot intend to distinguish between components that differ in name but notfunction.

In the following discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . .” Also, theterm “couple” or “couples” is intended to mean either an indirect ordirect connection. Thus, if a first device couples to a second device,that connection may be through a direct connection or through anindirect electrical connection via other devices and connections.

Reference to a singular item includes the possibility that there areplural of the same items present. More specifically, as used herein andin the appended claims, the singular forms “a,” “an,” “said” and “the”include plural references unless the context clearly dictates otherwise.It is further noted that the claims may be drafted to exclude anyoptional element. As such, this statement serves as antecedent basis foruse of such exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Lastly, it is to be appreciated that unless definedotherwise, all technical and scientific terms used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich this invention belongs.

“Active electrode” shall mean an electrode of an electrosurgical wandwhich produces an electrically-induced tissue-altering effect whenbrought into contact with, or close proximity to, a tissue targeted fortreatment.

“Return electrode” shall mean an electrode of an electrosurgical wandwhich serves to provide a current flow return path with respect to anactive electrode, and/or an electrode of an electrical surgical wandwhich does not itself produce an electrically-induced tissue-alteringeffect on tissue targeted for treatment.

A fluid conduit said to be “within” an elongate housing shall includenot only a separate fluid conduit that physically resides within aninternal volume of the elongate housing, but also situations where theinternal volume of the elongate housing is itself the fluid conduit.

“Abut” and “abutting” shall mean that two items are adjacent, but shallnot be read to require that two items actually touch.

Where a range of values is provided, it is understood that everyintervening value, between the upper and lower limit of that range andany other stated or intervening value in that stated range isencompassed within the invention. Also, it is contemplated that anyoptional feature of the inventive variations described may be set forthand claimed independently, or in combination with any one or more of thefeatures described herein.

All existing subject matter mentioned herein (e.g., publications,patents, patent applications and hardware) is incorporated by referenceherein in its entirety except insofar as the subject matter may conflictwith that of the present invention (in which case what is present hereinshall prevail). The referenced items are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present invention isnot entitled to antedate such material by virtue of prior invention.

DETAILED DESCRIPTION

Before the various embodiments are described in detail, it is to beunderstood that this invention is not limited to particular variationsset forth herein as various changes or modifications may be made, andequivalents may be substituted, without departing from the spirit andscope of the invention. As will be apparent to those of skill in the artupon reading this disclosure, each of the individual embodimentsdescribed and illustrated herein has discrete components and featureswhich may be readily separated from or combined with the features of anyof the other several embodiments without departing from the scope orspirit of the present invention. In addition, many modifications may bemade to adapt a particular situation, material, composition of matter,process, process act(s) or step(s) to the objective(s), spirit or scopeof the present invention. All such modifications are intended to bewithin the scope of the claims made herein.

FIG. 1 illustrates an electrosurgical system 100 in accordance with atleast some embodiments. In particular, the electrosurgical systemcomprises an electrosurgical wand 102 (hereinafter “wand”) coupled to anelectrosurgical controller 104 (hereinafter “controller”). The wand 102comprises an elongate housing 106 that defines distal end 108 where atleast some electrodes are disposed. The elongate housing 106 furtherdefines a handle or proximal end 110. The wand 102 further comprises aflexible multi-conductor cable 112 housing a plurality of electricalleads (not specifically shown in FIG. 1), and the flexiblemulti-conductor cable 112 terminates in a wand connector 114. As shownin FIG. 1, the wand 102 couples to the controller 104, such as by acontroller connector 120 on an outer surface 122 (in the illustrativecase of FIG. 1, the front surface).

Though not visible in the view of FIG. 1, in some embodiments the wand102 has one or more internal fluid conduits coupled to externallyaccessible tubular members. As illustrated, the wand 102 has a firstflexible tubular member 116 and a second flexible tubular member 118. Insome embodiments, the flexible tubular member 116 is used to providesaline to the distal end 108 of the wand. Likewise in some embodiments,flexible tubular member 118 is used to provide suction for aspiration atthe distal end 108 of the wand. In some embodiments, the flexibletubular member 116 is a hose having a 0.152 inch outside diameter, and a0.108 inch inside diameter, but other sizes may be equivalently used.Further, in some embodiments the flexible tubular member 118 is a hosehaving a 0.25 inch outside diameter, and a 0.17 inch internal diameter,but other sizes may be equivalently used.

Still referring to FIG. 1, the controller 104 controllably providesenergy to the wand 102 for the electrosurgical procedures (discussedmore below). A display device or interface panel 124 is visible throughthe outer surface 122 of the controller 104, and in some embodiments auser may select operational modes of the controller 104 by way of theinterface device 124 and related buttons 126.

In some embodiments the electrosurgical system 100 also comprises a footpedal assembly 130. The foot pedal assembly 130 may comprise one or morepedal devices 132 and 134, a flexible multi-conductor cable 136 and apedal connector 138. While only two pedal devices 132, 134 are shown,one or more pedal devices may be implemented. The outer surface 122 ofthe controller 104 may comprise a corresponding connector 140 thatcouples to the pedal connector 138. The foot pedal assembly 130 may beused to control various aspects of the controller 104, such as theoperational mode. For example, a pedal device, such as pedal device 132,may be used for on-off control of the application of radio frequency(RF) energy to the wand 102. A second pedal device, such as pedal device134, may be used to control and/or set the operational mode of theelectrosurgical system. For example, actuation of pedal device 134 mayswitch between energy levels. In yet still further embodiments, the wand102 may further comprise switches accessible on an outside portion,where the switches may control the operational modes of the controller104.

The electrosurgical system 100 of the various embodiments may have avariety of operational modes. One such mode employs Coblation®technology. In particular, the assignee of the present disclosure is theowner of Coblation® technology. Coblation® technology involves theapplication of an RF energy between one or more active electrodes andone or more return electrodes of the wand 102 to develop high electricfield intensities in the vicinity of the target tissue. The electricfield intensities may be sufficient to vaporize an electricallyconductive fluid over at least a portion of the one or more activeelectrodes in the region near the one or more active electrodes and thetarget tissue. Electrically conductive fluid may be inherently presentin the body, such as blood, puss, or in some cases extracellular orintracellular fluid. In other embodiments, the electrically conductivefluid may be a liquid or gas, such as isotonic saline. In a particularembodiment of wound treatment, the electrically conductive fluid isdelivered in the vicinity of the active electrode and/or to the targetsite by the wand 102, such as by way of the internal fluid conduit andflexible tubular member 116.

When the electrically conductive fluid is heated to the point that theatoms of the fluid vaporize faster than the atoms recondense, a gas isformed. When sufficient energy is applied to the gas, the atoms collidewith each other causing a release of electrons in the process, and anionized gas or plasma is formed (the so-called “fourth state ofmatter”). Stated otherwise, plasmas may be formed by heating a gas andionizing the gas by driving an electric current through the gas, or bydirecting electromagnetic waves into the gas. The methods of plasmaformation give energy to free electrons in the plasma directly,electron-atom collisions liberate more electrons, and the processcascades until the desired degree of ionization is achieved. A morecomplete description of plasma can be found in Plasma Physics, by R. J.Goldston and P. H. Rutherford of the Plasma Physics Laboratory ofPrinceton University (1995), the complete disclosure of which isincorporated herein by reference.

As the density of the plasma becomes sufficiently low (i.e., less thanapproximately 1020 atoms/cm³ for aqueous solutions), the electron meanfree path increases such that subsequently injected electrons causeimpact ionization within the plasma. When the ionic particles in theplasma layer have sufficient energy (e.g., 3.5 electron-Volt (eV) to 5eV), collisions of the ionic particles with molecules that make up thetarget tissue break molecular bonds of the target tissue, dissociatingmolecules into free radicals which then combine into gaseous or liquidspecies. Often, the electrons in the plasma carry the electrical currentor absorb the electromagnetic waves and, therefore, are hotter than theionic particles. Thus, the electrons, which are carried away from thetarget tissue toward the active or return electrodes, carry most of theplasma's heat, enabling the ionic particles to break apart the targettissue molecules in a substantially non-thermal manner.

By means of the molecular dissociation (as opposed to thermalevaporation or carbonization), the target tissue is volumetricallyremoved through molecular dissociation of larger organic molecules intosmaller molecules and/or atoms, such as hydrogen, oxygen, oxides ofcarbon, hydrocarbons and nitrogen compounds. The molecular dissociationcompletely removes the tissue structure, as opposed to dehydrating thetissue material by the removal of liquid within the cells of the tissueand extracellular fluids, as occurs in related art electrosurgicaldesiccation and vaporization. A more detailed description of themolecular dissociation can be found in commonly assigned U.S. Pat. No.5,697,882, the complete disclosure of which is incorporated herein byreference.

In addition to the Coblation® mode, the electrosurgical system 100 ofFIG. 1 may also in particular situations be useful for sealing bloodvessels, when used in what is known as a coagulation mode. Thus, thesystem of FIG. 1 may have an ablation mode where RF energy at a firstvoltage is applied to one or more active electrodes sufficient to effectmolecular dissociation or disintegration of the tissue, and the systemof FIG. 1 may have a coagulation mode where RF energy at a second, lowervoltage is applied to one or more active electrodes sufficient to heat,shrink, seal, fuse, and/or achieve homeostasis of severed vessels withinthe tissue.

The energy density produced by electrosurgical system 100 at the distalend 108 of the wand 102 may be varied by adjusting a variety of factors,such as: the number of active electrodes; electrode size and spacing;electrode surface area; asperities and/or sharp edges on the electrodesurfaces; electrode materials; applied voltage; current limiting of oneor more electrodes (e.g., by placing an inductor in series with anelectrode); electrical conductivity of the fluid in contact with theelectrodes; density of the conductive fluid; and other factors.Accordingly, these factors can be manipulated to control the energylevel of the excited electrons. Since different tissue structures havedifferent molecular bonds, the electrosurgical system 100 may beconfigured to produce energy sufficient to break the molecular bonds ofcertain tissue but insufficient to break the molecular bonds of othertissue.

A more complete description of the various phenomena can be found incommonly assigned U.S. Pat. Nos. 6,355,032; 6,149,120 and 6,296,136, thecomplete disclosures of which are incorporated herein by reference.

FIG. 2A illustrates a perspective view of the distal end 108 of wand 102in accordance with at least some embodiments. In particular, theillustrative system of FIG. 2 has an aspiration aperture 200, two activeelectrodes 202 and 204, a support member 206, a discharge aperture 208,and return electrode 210. Moreover, the illustrative distal end 108defines a width (labeled W in the figure) and a thickness (labeled T inthe figure). Each of the components will be discussed in turn.

The support member 206 is coupled to the elongate housing 106. In aparticular embodiment, the elongate housing 106 and handle 110 (FIG. 1)are made of a non-conductive plastic material, such as polycarbonate. Inyet other embodiments, the handle 110 and/or elongate housing 106 may beconstructed in whole or in part of metallic material, but the metallicmaterial is non-grounded and/or does not provide a return path forelectrons to the controller 104. Further, support member 206 is anon-conductive material resistant to degradation when exposed to plasma.In some cases support member 206 is made of a ceramic material (e.g.,alumina ceramic), but other non-conductive materials may be equivalentlyused (e.g., glass).

An illustrative two active electrodes 202 and 204 are coupled to thesupport member 206. Each active electrode is a metallic structure,around which plasma is created during use in some operational modes. Insome case, the wire is stainless steel, but other types of metallic wire(e.g., tungsten, molybdenum) may be equivalently used. As illustrated,each active electrode 202 and 204 is a loop of wire having a particulardiameter. Smaller diameter wire for the active electrodes advantageouslyresults in less thermal heating of the tissue, but there is a tradeoffwith wire strength, as smaller wire diameters tend to break and/or bendmore easily. In some embodiments, the wire diameter for each activeelectrode is between and including 0.008 and 0.015 inches, and in aparticular case 0.010 inches. Using active electrode 202 as exemplary ofboth active electrodes, the illustrative active electrode 202 comprisesa straight portion 212, as well as two standoff portions 214 (labeled214A and 214B). In accordance with at least some embodiments, the lengthof the straight portion 212 (i.e., standoff distance) is between andincluding 0.16 and 0.18 inches. Moreover, standoff portions 214 definean exposed length of between and including 0.010 and 0.050 inches, andin some cases between and including 0.015 and 0.025 inches. In theseembodiments the length defined by the standoff portions 214 is measuredfrom the surface 216 of the support member 206 to the central axis ofthe straight portion 202. It will be understood, however, that thestandoff portions 214 may extend into the support member 206, and thuswill be longer than the exposed length. For the example wire diametersand lengths of this paragraph, the exposed surface area of each activeelectrode (i.e., that portion residing outside the non-conductivesupport member 206) may be between and including 0.00447 and 0.04141square inches.

Still referring to active electrode 202 as illustrative of both activeelectrodes, the active electrode 202 is electrically coupled to thecontroller 104 (FIG. 1). In some cases, the active electrode 202 iscoupled to the controller by way of one of the standoff portions 214 andan insulated conductor (not specifically shown) that runs through theelongate housing 106. Thus, by way of the cable 112 (FIG. 1) andelectrical pins (shown in FIG. 10 below) in the connector 114 (FIG. 1),the active electrode 202 couples to the controller 104 (FIG. 1). In somecases the active electrodes all couple to the controller 104 by way ofthe same electrical pin, and in other cases each active electrode maycouple to the controller by way of its own electrical pin.

The straight portions of the active electrodes in FIG. 2A are parallel.However, the arrangement of FIG. 2A is merely illustrative. The activeelectrodes may take any suitable shape, and any suitable orientationbetween them. For example, the straight portions of the activeelectrodes may be coaxial. Further still, straight portions of theactive electrodes may form an obtuse angle. Yet further still, theactive electrodes may take any suitable form, such as a sinusoid betweenthe standoffs 214, or saw tooth pattern between the standoffs 214. Inmany cases, regardless of the form of the active electrodes, each activeelectrode 202 and 204 has approximately the same standoff distance froma plane defined by the outer surface 216 of the support member 214.

FIG. 2A further shows a discharge aperture 208. The discharge aperture208 as illustrated is rectangular, where the long dimension is alignedwith the width W. Rectangular shaped discharged apertures are merelyillustrative, and any suitable shape may be equivalently used (e.g.,circular, oval, square). Within the distal end 108 the aperture 208defines a fluid conduit 218. The fluid conduit is fluidly coupled withinthe elongate housing 106 to flexible tubular member 116 (FIG. 1),through which conductive fluid is pumped or gravity fed during use.Thus, during use, conductive fluid flows into the flexible tubularmember 116 (FIG. 1), through one or more fluid conduits (notspecifically shown) within the elongate housing 106, through the fluidconduits 218, and out of the discharge aperture 208.

In the various embodiments, the conductive fluid has conductivity abovea minimum threshold. More particularly, the conductive fluid will haveconductivity greater than 0.2 milli-Siemens per centimeter (mS/cm), insome cases greater than about 2 mS/cm, and in other cases greater thanabout 10 mS/cm. An example of the conductive fluid that may be used isisotonic saline, having conductivity of about 17 mS/cm. During wounddebridement, saline may flow at the rate of between and including 30 and70 milli-Liters per min (mL/min), but may vary depending on factors suchas: the pressure at the aspiration aperture 200; the geometry, materialproperty and configuration of the return electrode (discussed below);the geometry, material properties and configuration of the activeelectrodes 202 and 204; and the geometry, material properties andconfiguration of the support member 206.

The distal end 108 of the wand 102 further comprises a return electrodein the form of a conductive plate 210. In particular, the conductiveplate 210 abuts the discharge aperture 208, and in the embodiments ofFIG. 2A a portion of the conductive plate 210 at least partially definesthe discharge aperture 210. Further as shown, the conductive plate 210abuts the discharge aperture on an opposite side of the dischargeaperture than the active electrodes 202 and 204 and the support member206. For reasons discussed more below, at least a portion of theconductive plate resides over the discharge aperture 208. “Over” in thisinstance does not imply an orientation of the distal end 108 of the wand102; rather, “over” is only meant to imply that if the fluid conduit 218defined by the discharge aperture 208 was projected outward past thedischarge aperture 208, at least a portion of the conductive plate 210would reside within the projected area.

The conductive plate 210 is made of conductive material, whichconductive material forms a return path for electrical currentassociated with energy applied to the active electrodes. In some casesthe conductive plate 210 is made of stainless steel, but other types ofmetals (e.g., tungsten, molybdenum) may be equivalently used. Theillustrative conductive plate 210 is oriented such that at least some ofthe conductive fluid flowing through the fluid conduit 218 contacts theconductive plate 210 before contacting an adjacent wound or contactingthe active electrodes 202 and 204. For the particular embodiment of theconductive plate 210 forming at least a portion of the fluid conduit 218through which the conductive fluid flows, the upper (in the view of FIG.2) surface 220 of the conductive plate 210 defines an exposed surfacearea of greater than the exposed surface areas of the active electrodes.In some embodiments the exposed upper surface 220 of the conductiveplate 210 is at least twice the exposed surface area of the activeelectrodes, and in yet still other embodiments the exposed upper surface220 of the conductive plate 210 is at least eight times the exposedsurface area of the active electrodes.

Conductive plate 210 is electrically coupled to the controller 104 (FIG.1). In some cases, the conductive plate 210 is coupled to the controllerby way of an insulated conductor (not specifically shown) that runsthrough the elongate housing 106. Thus, by way of the cable 112 (FIG. 1)and electrical pins (shown in FIG. 10 below) in the connector 114 (FIG.1), the conductive plate 210 couples to the controller 104 (FIG. 1).

Having the conductive plate 210 at least partially define the fluidconduit 218, and further having the conductive plate 210 oriented insuch a way that conductive fluid exiting the discharge aperture 208encounters the conductive plate 210 and aids in operation of the wand102 for wound care in several ways. First, having the conductive plate210 at least partially form the fluid conduit 218 increases thelikelihood that the conductive fluid used to wet the electrodes makesgood contact with the conductive plate 210 operated as a returnelectrode. Stated otherwise, regardless of the orientation of the wand102 with respect to gravity, the conductive fluid provided to the woundtreatment site has a better chance of contacting the conductive plate210 operated as a return electrode due at least in part to theorientation of the conductive plate 210 relative to the dischargeaperture 208. Second, the conductive plate 210 residing over thedischarge aperture 208 helps direct the flowing conductive fluid towardthe active electrodes 202 and 204.

FIG. 2A also illustrates that a wand 102 in accordance with at leastsome embodiments further comprises an aspiration aperture 200. Theaspiration aperture 200 is fluidly coupled to the flexible tubularmember 118 (FIG. 1) by way of a lumen or fluid conduit (not specificallyshown) within the wand 102. Thus, and as the name implies, theaspiration aperture 204 is used to remove byproducts of wound treatmentusing the wand 102, such as removal of excess conductive fluid,molecularly disassociated tissue, and tissue separated from the woundbut otherwise still intact. As illustrated, the aspiration aperture 200has width approximately the same as the support member 206, and thusslightly wider than the active electrodes. In some cases, the width ofthe aspiration aperture 200 (the width labeled “W_(a)”) may be 0.591inches (about 15 millimeters (mm)) or less, in some case 0.394 inches(about 10 mm), and in other cases 0.197 inches (about 5 mm), dependingon the width of the distal end 108 of the wand and/or the number ofactive electrodes. Moreover, in some embodiments the height “H” of theaspiration aperture is a function of the standoff distance of the activeelectrodes. In some cases the height H may be greater than or equal tothree times (i.e., 3 to 1) the exposed length of the standoff portions,in other cases greater than or equal to six times (i.e., 6 to 1) theexposed length of the standoff portions, and in yet further casesgreater than or equal to ten times (i.e., 10 to 1) the exposed length ofthe standoff portions. For example, with an exposed length of thestandoff portions being in the range 0.015 to 0.025 inches, and a 6-to-1relationship, the aspiration aperture height may be on the order 0.01 to0.177 inches, respectively.

In operation of the various embodiments, aggressive aspiration iscontemplated to help remove larger pieces of tissue detached via theablative process but not molecularly disassociated (discussed morebelow). In some cases, the aspiration may be created by an appliedpressure between and including 100 millimeters of mercury (mmHg) and 400mmHg below atmospheric. However, in some cases aggravation of anexisting wound may occur if the aspiration aperture 200 is allowed toseal against the wound. In order to reduce the possibility of theaspiration aperture 200 sealing against the wound and/or patient, and asillustrated, in some embodiments at least a portion of the aspirationaperture is closer to the handle 110 (FIG. 1) than any portion of thedischarge apertures. In particular, portion 230 is closer to the handlethan portions 232A and 232B. Thus, when the distal end 108 is held in anorientation where the active electrodes 202 and 204 can interact withthe wound, the likelihood of the aspiration aperture 200 sealing againstthe wound and/or patient is drastically reduced. In yet still furtherembodiments, optional apertures 250 (three illustrative apertureslabeled 250A through 250C) may be implemented to ensure that if, bychance, the aperture 200 seals against the wound, the wound will not bysubjected to the full force of the aspiration suction as air may flowinto the apertures 250.

FIG. 2B shows an overhead cross-sectional view of the wand takensubstantially along lines 2B-2B of FIG. 2A. In particular, FIG. 2B showsthe aspiration aperture 200 as well as a fluid conduit 250. Inoperation, suction is provided to the flexible tubular member 118 (FIG.1), and flexible tubular member 118 either extends into the internalvolume of the wand 102 to become, or fluidly couples to, internal lumen252. Thus, conductive fluid, molecularly disassociated tissue, as wellas tissue pieces (discussed more below), are drawn through theaspiration aperture 200, into the fluid conduit 250, and eventually intothe lumen 252. The inventors of the present specification have foundthat particular lengths of the fluid conduit 250 between aspirationaperture 200 and the entrance to the internal lumen 252 work better thanothers. For example, if the length is too short, the fluid conduit 250is subject to clogging. Likewise, if the length is too long, zones oflittle or no airflow develop, again leading to clogs. In accordance withat least some embodiments the length of the fluid conduit 250 betweenthe aperture 200 and the entrance to the internal lumen 252 is afunction of the width W_(a) of the aspiration aperture at the widestpoint. More particularly, in accordance with at least some embodimentsthe internal walls 254 that define the fluid conduit 250 should besmoothly varying, and the length over which the width changes should beat least two times the change in width, and in most cases not longerthan eight times the change in width. Consider, as an example, a wandwhere the W_(a) is 0.39 inches (about 10 millimeters (mm)), and theinternal diameter of the lumen 252 is 0.118 inches (3 mm). In such asituation the change in internal width of the fluid conduit 250 betweenthe aspiration aperture 200 and the entrance to the lumen 252 will beabout 0.272 inches (about 7 mm), and in at least some embodiments thelength L over which the change in width is implemented should be atleast 0.544 inches (at least 14 mm). In a particular embodiment thechange in internal diameter to the length L is related as:

L=(W _(a) −ID)*2.3   (1)

where ID is the internal diameter of the lumen 252. Thus, for example, afluid conduit 270 associated with an aspiration aperture in operationalrelationship to a wand 102 with a single active electrode will have ashorter length than in the transition to the internal lumen than a fluidconduit 270 associated with an aspiration aperture in operationalrelationship to a wand 102 with three or more active electrodes.

The inventors of the present specification present the characteristic ofthe length L of FIG. 2B in terms of the width W_(a) of the aspirationaperture for sake of simplicity. Further, equivalent, relationships maybe determined, for example, based on changes in cross-sectional area ofthe fluid conduit 250 taking into account the height H (FIG. 2A) inrelation to the standoff distances implemented by the standoff portions214. Moreover, while FIG. 2B shows each wall 254 of the fluid conduit250 to be smoothly varying similar to a tangent function (i.e.,asymptotically approaching the W_(a) on one end, and asymptoticallyapproaching the internal diameter of the lumen 252 on the other), othersmoothly varying internal surfaces may be equivalently used (e.g.,straight line change in W_(a) from the aperture 200 to the internaldiameter of the lumen 252, asymptotically approaching the internaldiameter of the lumen 252).

FIG. 3 shows a front elevation view of the distal end 108 of the wand102 in accordance with at least some embodiments. In the view of FIG. 3,the conductive plate 210 is transparent (i.e., shown in dashed form) sothat the structural relationship behind (in this view) the conductiveplate 210 may be seen. In particular, the view of FIG. 3 shows that thedistal end of the conductive plate 210 resides over or occludes thedischarge aperture 208, and in this case distal end of the conductiveplate 210 occludes the full area of the discharge aperture 208. In othercases, the distal end of the conductive plate 210 occludes between halfand the full area of the discharge aperture 208. Stated a different way,if the discharge aperture 208 resides in and defines a plane (in thisview, the plane defined by the page), then when viewed perpendicularlyto the plane defined by the discharge aperture 208, the conductive plate210 occludes more than half an area defined by the discharge aperture.Thus, as conductive fluid is discharged through the discharge aperture208, the chance the conductive fluid makes good electrical contact withthe conductive plate 210 is high, regardless of the orientation of thewand 102 in relation to gravity.

FIG. 3 also shows a relationship between the active electrodes inaccordance with at least some embodiments. In particular, in accordancewith some embodiments the active electrodes 202 and 204 are offset alongthe thickness T. For example, as shown active electrode 202 is closer tothe aspiration aperture 200 than active electrode 204. While in someembodiments the active electrodes have the same elevation with respectto the thickness T, in the illustrative embodiments where an offset ispresent there is an overlap 300 of the active electrodes. The overlap300 of the active electrodes ensures that, in operation, the surfaceleft within the wound is less likely to have any ridges or elevationchanges caused by non-uniformity of the active electrodes.

FIG. 4 shows a side elevation view of the distal end 108 of a wand 102in accordance with various embodiments. In the view of FIG. 4, theoffset of the active electrodes 202 and 204 to enable the overlap 300(not shown in FIG. 4) is visible. In particular, active electrode 202 isoffset toward the aspiration aperture 200, while the active electrode204 is offset toward the discharge aperture 208. The offset of theactive electrodes 202 and 204 shown in FIG. 4 is merely illustrative,and the offsets may be equivalently swapped. Further, while FIG. 4 showsthe active electrodes 202 and 204 to be parallel, other embodiments,including embodiments with overlap, may be fashioned where the outerportions of the active electrodes form an angle of greater or lesserthan 180 degrees.

FIG. 4 also shows standoff distances of the active electrodes 202 and204. In particular, while the front face 400 of the support member 206defines a plane, and the standoff portions 214 define exposed lengthsuch that the straight portion of each active electrode 202 and 204 hasa standoff distance (the standoff labeled “S” in FIG. 4) from the frontface 400 that is approximately the same (i.e., the same withinmanufacturing tolerances).

FIG. 4 also shows aspects of directing conductive fluid toward theactive electrodes by the conductive plate. In particular, the conductiveplate 210 of FIG. 4 has a straight portion 410 and a lip portion 412 onthe distal end of the conductive plate 210. The lip portion 412 isdisposed over the discharge aperture 208. In the illustrative case ofFIG. 4, the lip portion 412 is formed by a curved portion 414 on thedistal end of the conductive plate. The lip portion 412 acts to directconductive fluid discharged from the discharge aperture 208 toward theactive electrodes, as illustrated by arrow 416. That is, the conductivefluid exits the discharge aperture 208 and encounters the lip portion412. The lip portion 412 is designed and constructed to change the flowdirection of at least some of the conductive fluid to flow more directlytowards the active electrodes. Thus, not only does the conductive fluidfully “wet” the conductive plate 210 acting as a return electrode, butthe likelihood of “wetting” the active electrodes is increased as well,independent of the orientation of the wand 102 in relation to gravity.Moreover, FIG. 4 illustrates that in some embodiments the distal end ofthe conductive plate 210 extends no further than the plane defined bythe front face 400.

FIG. 5 shows a side elevation view of the distal end 108 of a wand 102in accordance with other embodiments. In particular, FIG. 5 shows analternative arrangement of the conductive plate 210. The conductiveplate 210 of FIG. 5 has the straight portion 410 and the lip portion412, but in the illustrated embodiments the lip portion 412 is formed bya bend 500 in a medial portion of the conductive plate 210. Considerthat if the lip portion 412 defines a plane, the angle between the planecreated by the lip portion and the discharge aperture 208 is an acuteangle. Although the mechanical relationship of the conductive plate 210differs from that of FIG. 4, the outcome in a conductive fluid flowsense is the same. That is, conductive fluid exiting the dischargeaperture 208 encounters the lip portion 412, and is directed toward theactive electrodes 202 and 204. Thus, both the conductive plate 210acting as a return electrode, and the active electrodes 202 and 204,have a better chance of being fully “wetted” for purposes of plasmacreation.

FIG. 5 also illustrates that in some embodiments the conductive plate210 is insulated on a side opposite the discharge aperture 208 (i.e.,the bottom side 510). In particular, the conductive plate 210 is coveredon the bottom side 510 with an insulating material 512. In some casesthe insulating material is an extension of the non-conductive outerhousing 514. In other embodiments, the insulating material 512 may beany non-conductive or partially non-conductive material. For example,the conductive plate 210 could be anodized, dipped in an insulatingmaterial, have an insulating material glued thereon, and the like. Theembodiments with insulating material 510 are not limited to embodimentswhere the lip portion 412 is created by a bend 500. The insulatingmaterial 512 may be used with any configuration of the conductive plate210. Additionally, in any configuration of conductive plate 210, thebottom side 510 may act as a guide surface that engages the tissue to betreated as the wand is translated across the wound.

FIG. 6 shows a cross-sectional elevation view of the distal end 108 ofthe wand 102 taken substantially along line 6-6 of FIG. 3. Inparticular, FIG. 6 shows that, in accordance with some embodiments, theaspiration aperture 200 defines a wide opening, but the fluid conduit250 within the distal end tapers downward to a narrower conduit 602.However, in other embodiments (e.g., as shown in FIG. 2B) a lumen mayreside within the elongate housing 106 and fluidly couple to the fluidconduit 250. FIG. 6 further illustrates the support member 206 coupledto an outer face 606 of the distal end 108 of the wand 102. In theseembodiments, the support member 206 may couple by any suitable means,such as an adhesive. In other cases, the support member 206 and distalend of the elongate housing may have mating mechanical features thatfully or partially retain the support member 206. Moreover, the distalend 108 defines a cavity region 608 between the fluid conduit 250associated with the aspiration aperture 200, and the fluid conduit 218associated with the discharge aperture 208. Within the cavity 608 mayreside one or more electrical leads 610 that electrically couple theactive electrodes 202 and 204 to the controller. Though not visible inthe view of FIG. 6, the cavity 608 may also contain an electrical leadthat electrically couples the conductive plate 210 to the controller.

FIG. 6 also illustrates that, in at least some embodiments, the fluidconduit 218 associated with the discharge aperture 208 is partiallydefined by the conductive plate 210. In particular, in the illustratedembodiments portion 610 of conductive plate 210 extends into and atleast partially defines the fluid conduit 218. In this way, theconductive fluid flowing in the fluid conduit contacts the conductiveplate 210 acting as a return electrode even before being dischargedthrough the discharge aperture 208. In other embodiments, the fluidconduit 218 may be fully defined by the material that makes up theelongate housing 106 (e.g., polycarbonate), and the conductive plate 210may be positioned in such a way that the conductive fluid does notcontact the conductive plate until after the fluid has dischargedthrough the discharge aperture 208.

FIG. 7 shows a side elevation view of the distal end 108 of wand 102 inuse for wound care. In particular, the wand 102 is shown abutting wound700, such as a diabetic foot ulcer. In operation, electrical energy isapplied to the active electrodes, but here only active electrode 204 isvisible. The energy in the example of FIG. 7 is sufficient to createplasma near the active electrodes, which thus molecularly disassociatestissue that comes in relatively close contact with the activeelectrodes. However, the arrangement of the active electrodes is suchthat the reach of the plasma is less than the standoff distance of eachactive electrode from the plane defined by the front face of the supportmember 206. Thus, when operated with sufficient energy to create plasma,as the wand is translated along the wound (as illustrated by arrow 710)the active electrodes act to slice portions of the tissue via theplasma-mediated ablative process, rather than attempting to completelymolecularly disassociate the tissue. The result is strips of tissue 702(multiple strips labeled 702A through 702C) are created, and whichstrips of tissue 702 (as well as conductive fluid and remnants of tissuemolecularly disassociated) are drawn into the aspiration aperture 200 bythe aspiration action. The inventors of the present specification havefound that the situation illustrated by FIG. 7 is particularly efficientat debridement of wounds (e.g., removing biofilm). While not wanting tobe tied to any particular theory of why the treatment works well, it isbelieved that the plasma created by the wand 102 is particularlyefficient at destroying bacteria. Moreover, it is believed that the“slicing” action in combination with the aggressive aspiration helpsensure that the potentially bacteria contaminated strips of tissue 702either: do not contact the remaining wound portions after removalbecause of motion and aspiration (thus reducing the chances ofre-infecting the wound); or, if contact is present, that the contact isfor such a short duration, or the contact is on side of the strips oftissue where bacteria have been killed by the plasma, that the chancesof re-infection of the wound 700 are low.

The various embodiments discussed to this point have had two activeelectrodes. However, other numbers of active electrodes may beequivalently used. For example, FIG. 8 shows an end elevation view ofthe distal end 108 of wand 102 comprising a single active electrode 800,and correspondingly the width of the discharge aperture (not visible)the conductive plate 802 and aperture 804 are smaller as well. Likewise,FIG. 9 shows an end elevation view of the distal end 108 of wand 102comprising an illustrative three active electrodes 900, 902 and 904, andcorrespondingly the width of the discharge aperture 906 (illustrativelyvisible in these embodiments) the conductive plate 908 and aperture 910are larger as well. One may use the wand 102 having a distal end 108 asshown in FIG. 8 as the situation dictates, for example for smallerwounds or wounds in hard to reach locations. Likewise, one may use thewand 102 having a distal end 108 as shown in FIG. 9 as the situationdictates, for example larger wounds and/or areas easier to reach.

As illustrated in FIG. 1, flexible multi-conductor cable 112 (and moreparticularly its constituent electrical leads) couple to the wandconnector 114. Wand connector 114 couples the controller 104, and moreparticularly the controller connector 120. FIG. 10 shows both across-sectional view (right) and an end elevation view (left) of wandconnector 114 in accordance with at least some embodiments. Inparticular, wand connector 114 comprises a tab 1000. Tab 1000 works inconjunction with a slot on controller connector 120 (shown in FIG. 11)to ensure that the wand connector 114 and controller connector 120 onlycouple in one relative orientation. The illustrative wand connector 114further comprises a plurality of electrical pins 1002 protruding fromwand connector 114. In many cases, the electrical pins 1002 are coupledone each to an electrical lead of electrical leads 1004, which leads areelectrically coupled to active and return electrodes. Stated otherwise,in a particular embodiment each electrical pin 1002 couples to a singleelectrical lead, and thus each illustrative electrical pin 1002 couplesto a single electrode of the wand 102. In other cases, a singleelectrical pin 1002 couples to multiple electrodes (e.g., multipleactive electrodes, or multiple return electrodes) on the electrosurgicalwand 102. While FIG. 10 shows four illustrative electrical pins, in someembodiments as few as two electrical pins, and as many as 26 electricalpins, may be present in the wand connector 114.

FIG. 11 shows both a cross-sectional view (right) and an end elevationview (left) of controller connector 120 in accordance with at least someembodiments. In particular, controller connector 120 comprises a slot1100. Slot 1100 works in conjunction with a tab 1000 on wand connector114 (shown in FIG. 10) to ensure that the wand connector 114 andcontroller connector 120 only couple in one orientation. Theillustrative controller connector 120 further comprises a plurality ofelectrical pins 1102 residing within respective holes of controllerconnector 120. The electrical pins 1102 are coupled to terminals of avoltage generator within the controller 104 (discussed more thoroughlybelow). When wand connector 114 and controller connector 120 arecoupled, each electrical pin 1102 couples to a single electrical pin1002. While FIG. 11 shows only four illustrative electrical pins, insome embodiments as few as two electrical pins and as many as 26electrical pins may be present in the wand connector 120.

While illustrative wand connector 114 is shown to have the tab 1000 andmale electrical pins 1002, and controller connector 120 is shown to havethe slot 1100 and female electrical pins 1102, in alternativeembodiments the wand connector has the female electrical pins and slot,and the controller connector 120 has the tab and male electrical pins,or other combination. In other embodiments, the arrangement of the pinswithin the connectors may enable only a single orientation forconnection of the connectors, and thus the tab and slot arrangement maybe omitted. In yet still other embodiments, other mechanicalarrangements to ensure the wand connector and controller connectorcouple in only one orientation may be equivalently used.

FIG. 12 illustrates a controller 104 in accordance with at least someembodiments. In particular, FIG. 12 illustrates the controller 104coupled to the wand 102, where the wand 102 is shown in simplified formcomprising the active electrodes 202/204, the conductive plate 210acting as a return electrode 210, and electrical leads coupled to thecontroller 104. The controller 104 comprises a processor 1200. Theprocessor 1200 may be a microcontroller, and therefore themicrocontroller may be integral with random access memory (RAM) 1202,read-only memory (ROM) 1204, digital-to-analog converter (D/A) 1206,digital outputs (D/O) 1208 and digital inputs (D/I) 1210. The processor1200 may further provide one or more externally available peripheralbusses, such as a serial bus (e.g., I²C), parallel bus, or other bus andcorresponding communication mode. The processor 1200 may further beintegral with a communication logic 1212 to enable the processor 1200 tocommunicate with external devices, as well as internal devices, such asdisplay device 124. Although in some embodiments the controller 104 mayimplement a microcontroller, in yet other embodiments the processor 1200may be implemented as a standalone central processing unit incombination with individual RAM, ROM, communication, D/A, D/O and D/Idevices, as well as communication port hardware for communication toperipheral components.

ROM 1204 stores instructions executable by the processor 1200. Inparticular, the ROM 1204 may comprise a software program that implementsthe various embodiments of controlling the voltage generator 1216(responsive to commands from the user), as well as interfacing with theuser by way of the display device 124 and/or the foot pedal assembly 130(FIG. 1). The RAM 1202 may be the working memory for the processor 1200,where data may be temporarily stored and from which instructions may beexecuted. Processor 1200 couples to other devices within the controller104 by way of the D/A converter 1206 (e.g., the voltage generator 1216),digital outputs 808 (e.g., the voltage generator 1216), digital inputs1210 (i.e., push button switches 126, and the foot pedal assembly 130(FIG. 1)), and other peripheral devices.

Voltage generator 1216 generates selectable alternating current (AC)voltages that are applied to the electrodes of the wand 102. In variousembodiments, the voltage generator defines two terminals 1224 and 1226.The terminals 1224 and 1226 may couple to active electrodes and returnelectrodes. As an example, terminal 1224 couples to illustrative activeelectrodes 202 and 204, and terminal 1226 couples to the conductiveplate 210 acting as return electrode. In accordance with the variousembodiments, the voltage generator generates an alternating current (AC)voltage across the terminals 1224 and 1226. In at least some embodimentsthe voltage generator 1216 is electrically “floated” from the balance ofthe supply power in the controller 104, and thus the voltage onterminals 1224, 1226, when measured with respect to the earth ground orcommon (e.g., common 1228) within the controller 104, may or may notshow a voltage difference even when the voltage generator 1216 isactive.

The voltage generated and applied between the active terminal 1224 andreturn terminal 1226 by the voltage generator 1216 is a RF signal that,in some embodiments, has a frequency of between about 5 kilo-Hertz (kHz)and 20 Mega-Hertz (MHz), in some cases being between about 30 kHz and2.5 MHz, often between about 100 kHz and 200 kHz. The RMS (root meansquare) voltage generated by the voltage generator 816 may be in therange from about 5 Volts (V) to 1000 V, preferably being in the rangefrom about 10 V to 500 V, often between about 100 V to 350 V dependingon the active electrode size and the operating frequency. Thepeak-to-peak voltage generated by the voltage generator 1216 forablation for wound treatment in some embodiments is a square wave formin the range of 10 V to 2000 V and in some cases in the range of 100 Vto 1800 V and in other cases in the range of about 28 V to 1200 V, oftenin the range of about 100 V to 320V peak-to-peak (again, depending onthe electrode size and the operating frequency).

Still referring to the voltage generator 1216, the voltage generator1216 delivers average energy levels ranging from several milliwatts tohundreds of watts per electrode, depending on the voltage applied forthe target tissue being treated, and/or the maximum allowed temperatureselected for the wand 102. The voltage generator 1216 is configured toenable a user to select the voltage level according to the specificrequirements of a particular procedure. A description of one suitablevoltage generator 1216 can be found in commonly assigned U.S. Pat. Nos.6,142,992 and 6,235,020, the complete disclosure of both patents areincorporated herein by reference for all purposes.

In some embodiments, the various operational modes of the voltagegenerator 1216 may be controlled by way of digital-to-analog converter1206. That is, for example, the processor 1200 may control the outputvoltage by providing a variable voltage to the voltage generator 1216,where the voltage provided is proportional to the voltage generated bythe voltage generator 1216. In other embodiments, the processor 1200 maycommunicate with the voltage generator by way of one or more digitaloutput signals from the digital output 1208 device, or by way of packetbased communications using the communication device 1212 (connection notspecifically shown so as not to unduly complicate FIG. 12).

FIG. 13 shows a method in accordance with at least some embodiments. Inparticular, the method starts (block 1300) and comprises: flowing aconductive fluid within a fluid conduit disposed within aelectrosurgical wand, the conductive fluid is discharged through adischarge aperture in the direction of a return electrode, and thereturn electrode directs at least a portion of the conductive fluidtoward an active electrode (block 1302); applying electrical energybetween the active and return electrodes (block 1304); forming,responsive to the energy, a plasma proximate to the active electrode(block 1306); and treating a wound by placing the active electrodeagainst the wound, and translating the active electrode along the wound(block 1308). Thereafter the method ends (block 1310).

While preferred embodiments of this disclosure have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the scope or teaching herein. The embodimentsdescribed herein are exemplary only and are not limiting. Because manyvarying and different embodiments may be made within the scope of thepresent inventive concept, including equivalent structures, materials,or methods hereafter though of, and because many modifications may bemade in the embodiments herein detailed in accordance with thedescriptive requirements of the law, it is to be understood that thedetails herein are to be interpreted as illustrative and not in alimiting sense.

1. An electrosurgical wand comprising: an elongate housing that definesa handle end and a distal end; a connector comprising a first and secondelectrical pins; an aspiration aperture on the distal end of theelongate housing, the aspiration aperture fluidly coupled to a firstfluid conduit, the first fluid conduit within the elongate housing; adischarge aperture on the distal end of the elongate housing, thedischarge aperture fluidly coupled to a second fluid conduit, and thesecond fluid conduit within the elongate housing; a first activeelectrode of conductive material on the distal end of the elongatehousing, the first active electrode between the discharge aperture andthe aspiration aperture, and the first active electrode electricallycoupled to the first electrical pin; and a conductive plate that abutsthe discharge aperture, at least a portion of the conductive platedisposed over the discharge aperture, and the conductive plateelectrically coupled to the second electrical pin.
 2. Theelectrosurgical wand of claim 1 wherein the conductive plate defines alip portion, and wherein at least a portion of the lip portion isdisposed over the discharge aperture.
 3. The electrosurgical wand ofclaim 2 wherein the lip portion is defined between a distal end of theconductive plate and a bend in the conductive plate.
 4. Theelectrosurgical wand of claim 2 wherein the conductive plate has acurved portion and the lip portion is the distal end of the conductiveplate.
 5. The electrosurgical wand of claim 1 further comprising: thefirst active electrode defines a first exposed surface area; and theconductive plate defines a second exposed surface area greater than thefirst exposed surface area.
 6. The electrosurgical wand of claim 1wherein when viewed perpendicularly to a plane defined by the dischargeaperture, the conductive plate occludes more than half an area definedby the discharge aperture.
 7. The electrosurgical wand of claim 1wherein first active electrode further comprises a loop of wire thatdefines a straight portion and two standoff portions.
 8. Theelectrosurgical wand of claim 7 wherein the first active electrode has astandoff distance between and including 0.010 and 0.050 inches.
 9. Theelectrosurgical wand of claim 7 wherein the first active electrode has astandoff distance of between and including 0.015 and 0.025 inches. 10.The electrosurgical wand of claim 7 wherein the loop of wire has adiameter of between and including 0.008 and 0.015 inches.
 11. Theelectrosurgical wand of claim 7 wherein the loop of wire has a diameterof 0.010 inches.
 12. The electrosurgical wand of claim 1 wherein atleast a portion of the aspiration aperture is closer to the handle thanthe any portion of the discharge aperture.
 13. The electrosurgical wandof claim 1 further comprising: the distal end of the elongate housingdefines a width and a thickness; wherein first active electrode furthercomprises a loop of wire that defines a first straight portion; a secondactive electrode that comprises a loop of wire that defines a secondstraight portion; and the first and second straight portions are alignedalong the width such that, when viewed along the thickness, the firstand second straight portions overlap.
 14. The electrosurgical wand ofclaim 13 wherein the first straight portion and the second straightportion are parallel.
 15. The electrosurgical wand of claim 1 whereinthe aspiration aperture defines an aperture width, and wherein thesecond fluid conduit transitions in width from the aperture width to aninternal width over a length not less than two times the differencebetween the aperture width and the internal width.
 16. A methodcomprising: flowing a conductive fluid within a fluid conduit disposedwithin a electrosurgical wand, the conductive fluid is dischargedthrough a discharge aperture in the direction of a return electrode, andthe return electrode directs at least a portion of the conductive fluidtoward an active electrode; applying electrical energy between theactive and return electrodes; forming, responsive to the energy, aplasma proximate to the active electrode; and treating a wound byplacing the active electrode adjacent to the wound, and translating theactive electrode along the wound.
 17. The method of claim 16 whereinflowing further comprises flowing the conductive fluid past the returnelectrode in the form of a conductive plate with a distal bend.
 18. Themethod of claim 16 wherein flowing further comprises flowing theconductive fluid past the return electrode in the form of a conductiveplate with distal curvature.
 19. The method of claim 16 wherein flowingfurther comprises flowing the conductive fluid such that the conductivefluid is directed toward the active electrode in the form of loop ofwire.
 20. The method of claim 16 further comprising aspirating through afluid conduit in the electrosurgical wand, the aspirating proximate tothe discharge aperture.
 21. The method of claim 20 wherein treating thewound comprises detaching at least one wound tissue strip from the woundand aspirating the at least one strip away from the wound such that theat least one strip does not substantially contact an underlyingremaining wound portion.
 22. The method of claim 21 wherein detachingthe at least one wound tissue strip comprises ablating at least aportion of the wound without completely molecularly dissociating the atleast one strip.
 23. The method of claim 20 wherein treating the woundcomprises debriding at least a portion of the wound and aspirating aplurality of wound tissue strips away from the wound.
 24. The method ofclaim 23 wherein the steps of debriding and aspirating further compriseremoving a substantial concentration of bacteria from the wound.
 25. Themethod of claim 16 further comprising engaging the wound with a bottomsurface of the return electrode such that the bottom surface guides thewand during the translating step.
 26. A system comprising: anelectrosurgical controller, the electrosurgical controller configured toproduce radio frequency (RF) energy at an active terminal with respectto a return terminal; an electrosurgical wand coupled to theelectrosurgical controller, the electrosurgical wand comprising: anelongate housing that defines a handle end and a distal end; anaspiration aperture on the distal end of the elongate housing, theaspiration aperture fluidly coupled to a first fluid conduit, the firstfluid conduit within the elongate housing; a discharge aperture on thedistal end of the elongate housing, the discharge aperture fluidlycoupled to a second fluid conduit, and the second fluid conduit withinthe elongate housing; a first active electrode of conductive material onthe distal end of the elongate housing, the first active electrodebetween the discharge aperture and the aspiration aperture, and thefirst active electrode electrically coupled to active terminal of theelectrosurgical controller; and a conductive plate that abuts thedischarge aperture, at least a portion of the conductive plate disposedover the discharge aperture, and the conductive plate electricallycoupled to the return terminal of the electrosurgical controller. 27.The electrosurgical wand of claim 26 wherein the conductive platedefines a plane, and wherein an angle between the plane and thedischarge aperture is an acute angle.
 28. The electrosurgical wand ofclaim 26 wherein the conductive plate defines a straight portion and alip portion, and wherein at least a portion of the lip portion isdisposed over the discharge aperture.
 29. The electrosurgical wand ofclaim 28 wherein the lip portion is defined between a distal end of theconductive plate and a bend in a medial portion of the conductive plate.30. The electrosurgical wand of claim 28 wherein the conductive platehas a curved portion and the lip portion is the distal end of theconductive plate.
 31. The electrosurgical wand of claim 26 furthercomprising: the first active electrode defines a first exposed surfacearea; and the conductive plate defines a second exposed surface areagreater than the first exposed surface area.
 32. The electrosurgicalwand of claim 26 wherein when viewed perpendicularly to a plane definedby the discharge aperture, the return electrode occludes more than halfan area defined by the discharge aperture.
 33. The electrosurgical wandof claim 26 wherein first active electrode further comprises a loop ofwire that defines a straight portion and two standoff portions.
 34. Theelectrosurgical wand of claim 26 wherein at least a portion of theaspiration aperture is closer to the handle than the any portion of thedischarge aperture.
 35. The electrosurgical wand of claim 26 furthercomprising: the distal end of the elongate housing defines a width and athickness; wherein first active electrode further comprises a loop ofwire that defines a first straight portion; a second active electrodethat comprises a loop of wire that defines a second straight portion;and the first and second straight portions are aligned along the widthsuch that, when viewed along the thickness, the first and secondstraight portions overlap.
 36. The electrosurgical wand of claim 35wherein the first straight portion and the second straight portion areparallel.